> Marshall Brass #290, available anyplace that does RV propane
> work.

That's the one.  There are two things you need on the regulator:
It must be "horizontal" vs "vertical"--the drains for both
stages must point "down."  And it needs a cover--to keep the
drains clean.  That's a white plastic snap-on extra; another
$3-4.

Oh, three things:  it must be "two stage."

Both are pictured:
http://www.rvadenver.com/lp_gas_accessories.htm
GoWesty's includes the covers:
http://gowesty.com/ec_view_details.php?id=2448&category_id=380&category_parent_id=

Richard